Thermally decomposable polymer compositions incorporating thermally activated base generators

ABSTRACT

Embodiments in accordance with the present invention provide sacrifical polymer compositions and methods for fabricating electronic devices using such sacrifical polymer compositions where such methods include (1) providing a tacky sacrifical polymer composition that holds components in a desired alignment to one another, (2) providing solder fluxing for effecting electrical coupling; and (3) thermal decomposition or depolymerization of the sacrificial polymer composition to provide essentially residue free surfaces.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Non-provisional application and claims the benefitof priority to prior Provisional application Ser. No. 61/497,232 filedJun. 15, 2011, the entire contents of which are incorporated herein byreference.

TECHNICAL FIELD

The present invention relates generally to thermally decomposablepolymer compositions and more specifically to such compositions thatincorporate a thermally activated base generator (TABG) where suchcompositions are useful in forming microelectronic structures andassemblies where for such assemblies the thermally decomposable polymercompositions provide both tackiness and solder fluxing.

BACKGROUND

While assembled electronic circuitry has been dramatically reduced insize the use of soldering as a method for forming both an electrical andfixable attachment of electronic components to a substrate has remainedquite prevalent. However, such attachments generally require that theelectronic components be held in desired positions prior to completingthe aforementioned fixable attachments.

A number of solutions for holding components in such desired positionshave been developed and used with some success. For example, it is knownto use a tack agent to temporarily secure such components in desiredpositions while solder bond or solder ball connections are made throughthe application of heat. However, generally such tack agent remains as acontaminant that requires the assembly to be subjected to an extraprocessing step designed to remove such contamination. For some of theaforementioned solutions, a fluxing agent is provided separately fromthe tack agent, for example by applying such fluxing agent in a distinctapplication step, separate from the application of the tack agent. Inother solutions the fluxing agent is provided in a combination with thetack agent, for example where a solder paste is used as the tack agentand fluxing agent is either added thereto or pre-reacted therewith.

In still other solutions, a tack agent and a di-carboxylic acid fluxingagent are admixed where upon soldering, the tack agent eithervolatilizes or decomposes (see, U.S. Pat. No. 5,177,134). However, as adi-carboxylic acid fluxing agent is taught, it is likely that even smallamounts of contamination from such di-carboxylic acid fluxing agent canremain and cause reliability issues if a separate cleaning step is notemployed. In US Published Application No. 2009/0294515, embodimentswhere either specialized process equipment is required for fluxlesssolder bonding or a carboxylic acid fluxing agent are employed.Therefore new solutions that eliminate the need for such specializedequipment by providing tacking properties and a non-carboxylic acidfluxing agent to achieve desirable solder reflow are needed.

DETAILED DESCRIPTION

Exemplary embodiments in accordance with the present invention aredescribed with reference to the Examples and Claims providedhereinafter. Such embodiments encompassing a polymer composition thatprovides both tacking properties and a non-carboxylic acid fluxingagent, as well as methods for using such polymer compositions forforming microelectronic and/or optoelectronic devices. Variousmodifications, adaptations or variations of such exemplary embodimentsdescribed herein may become apparent to those skilled in the art as suchare disclosed. It will be understood that all such modifications,adaptations or variations that rely upon the teachings of the presentinvention, and through which these teachings have advanced the art, areconsidered to be within the scope and spirit of the present invention.

As used herein, the articles “a,” “an,” and “the” include pluralreferents unless otherwise expressly and unequivocally limited to onereferent.

As used herein, the term “thermal base generator” and similar terms,such as, “thermally activated base generator” and “thermal initiator”means a material that generates one or more bases after heating to aneffective temperature.

As used herein, the terms “group” or “groups” when used in relation to achemical compound and/or representative chemical structure/formula, meanan arrangement of one or more atoms.

As used herein, molecular weight values of polymers, such as weightaverage molecular weights (M_(w)) and number average molecular weights(M_(n)), are determined by gel permeation chromatography usingpolystyrene standards for calibration.

As used herein, polydispersity index (PDI) values represent a ratio ofthe weight average molecular weight (M_(w)) to the number averagemolecular weight (M_(n)) of the polymer (i.e., M_(w)/M_(n)).

As used herein, and unless otherwise stated, polymer glass transitiontemperature (T_(g)) values are determined by differential scanningcalorimetry, in accordance with American Society for Testing andMaterials (ASTM) method number D3418.

Unless otherwise indicated, all ranges or ratios disclosed herein are tobe understood to encompass any and all subranges or subratios subsumedtherein. For example, a stated range or ratio of “1 to 10” should beconsidered to include any and all subranges between (and inclusive of)the minimum value of 1 and the maximum value of 10; that is, allsubranges or subratios beginning with a minimum value of 1 or more andending with a maximum value of 10 or less, such as but not limited to, 1to 6.1, 3.5 to 7.8, and 5.5 to 10.

Other than in the operating examples, or where otherwise specificallyindicated, all numbers expressing quantities of ingredients, reactionconditions, and so forth used in the specification and claims are to beunderstood as being modified in all instances by the term “about” totake into account the uncertainties associated with determining suchvalues.

As used herein the term “hydrocarbyl” and similar terms, such as“hydrocarbyl group” means a radical of a group that contains carbon andoptionally hydrogen, non-limiting examples being alkyl, cycloalkyl,polycycloalkyl, aryl, aralkyl, alkaryl, alkenyl, cycloalkenyl,polycycloalkenyl, alkynyl, cycloalkynyl and polycycloalkynyl. The term“halohydrocarbyl” as used herein means a hydrocarbyl group where atleast one hydrogen covalently bonded to a carbon has been replaced by ahalogen. The term “perhalocarbyl” as used herein means a hydrocarbylgroup where all such hydrogens have been replaced by a halogen. Inaddition, the term “heterohydrocarbyl” as used herein means ahydrocarbyl group where at least one carbon atom has been replaced witha hetero atom such as oxygen, nitrogen, silicon and/or sulfur.

As used herein, the term “alkyl” means a linear or branched acyclic orcyclic, saturated hydrocarbon group having a carbon chain length of fromC₁ to C₂₅. Nonlimiting examples of suitable alkyl groups include methyl,ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl,pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl,tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl,nonadecyl, isocanyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl,cycloheptyl and cyclooctyl. As used herein, the term “heterocycloalkyl”means a cycloalkyl group in which one or more carbons of the cyclic ringhas been replaced with a hetero atom, such as oxygen, nitrogen, siliconand/or sulfur. Representative heterocycloalkyl groups include but arenot limited to tetrahydrofuranyl, tetrahydropyranyl, morpholinyl, andpiperidinyl.

As used herein, the term “alkylene” means a bivalent alkyl group, asdescribed above, having a carbon chain length of from C₂ to C₂₅.

As used herein, the term “aryl” means aromatic groups that include,without limitation, phenyl, biphenyl, benzyl, xylyl, naphthalenyl,anthracenyl, and the like. As used herein, the term “heteroaryl” meansan aryl group in which one or more carbons of the aromatic ring or ringshas been replaced with a hetero atom, such as oxygen, nitrogen, siliconand/or sulfur. Representative heteroaryl groups include but are notlimited to furanyl, pyranyl and pyridinyl.

The terms “alkaryl” and “aralkyl” are used herein interchangeably andmean a linear or branched acyclic alkyl group substituted with at leastone aryl group, for example, phenyl, and having an alkyl carbon chainlength of C₁ to C₂₅. It will further be understood that the aboveacyclic alkyl group can be a haloalkyl or perhaloalkyl group.

As used herein, the term “alkenyl” means a linear or branched acyclic orcyclic hydrocarbon group having one or more double bonds and having analkenyl carbon chain length of C₂ to C₂₅. Non-limiting examples ofalkenyl groups include, among others, vinyl, allyl, propenyl, butenyl,pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl,dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl,heptadecenyl, octadecenyl, nonadecenyl, and isocenyl, and the like.

As used herein, the term “alkynyl” means a linear or branched acyclic orcyclic hydrocarbon group having one or more carbon-carbon triple bondsand having an alkynyl carbon chain length of C₂ to C₂₅. Representativealkynyl groups, include but are not limited to, ethynyl, 1-propynyl,2-propynyl, 1-butynyl, 2-butynyl, pentynyl, heptynyl, octynyl, nonynyl,decynyl, undecynyl, dodecynyl, tridecynyl, tetradecynyl, pentadecynyl,hexadecynyl, heptadecynyl, octadecynyl, nonadecynyl, isocynyl, and thelike.

As used herein, recitations of “linear or branched” groups, such aslinear or branched alkyl, will be understood to include a methylenegroup, groups that are linear, such as linear C₂-C₂₅ alkyl groups, andgroups that are appropriately branched, such as branched C₃-C₂₅ alkylgroups.

The features that characterize embodiments of the present invention arepointed out with particularity in the claims, which form a part of thisdisclosure. These and other features of such embodiments, theiroperating advantages and uses will be more fully understood from thedescription of such embodiments herein below.

Embodiments in accordance with the present invention provide sacrificialpolymer compositions that encompass, among other things, theaforementioned sacrificial polymer, a thermally activated base generatormoiety and a solvent. With regard to the sacrificial polymer, thesepolymers encompass both commercially available polyalkylene carbonates(e.g. polyethylene carbonate and polypropylene carbonate from Novomer,Inc. of Waltham Mass., and polyethylene carbonate, polypropylenecarbonate, polybutylene carbonate, polycyclohexylene carbonate and apolybutylene carbonate/polycyclohexylene carbonate blend from EmpowerMaterials, Inc., of New Castle, Del.), as well as polymers derived frompolycyclic 2,3-diol monomers in accordance with any of Formulae A-G,A1-F1 and D1a-F1a shown below. Such polymers referred to aspolynorbornanediol carbonates.

For each monomer represented by Formulae A, B and C, n is independently0, 1 or 2, each of R¹, R², R³ and R⁴ is independently selected fromhydrogen or a hydrocarbyl group containing, without limitation, from 1to 25 carbon atoms, each of R⁵ and R⁶ are independently selected from—(CH₂)_(p)—OH, where p is 0, 1, 2 or 3, and each of X and X′ isindependently selected from —CH₂—, —CH₂—CH₂— and —O—, where each X′ is,if present, oriented the same or opposite the orientation of X. For someembodiments in accordance with the present invention, p is 1, 2 or 3 forat least one of R⁵ and R⁶. In some embodiments of the present invention,the sum of the p for R⁵ and p for R⁶ is either 1 or 3.

As shown in Formulae A, B and C, each X group is depicted as extendingupward out of the page. With Formula A, R⁵ and R⁶ are each also depictedas extending upward out of the page, and as such are cis- to one anotherand are exo-relative to the X group. Formula A, therefore is referred toas a polycyclic cis-exo 2,3-diol monomer. In Formula B, R⁵ and R⁶ areeach depicted as extending downward into the page, and as such are cis-to one another and are endo-relative to the X group. Formula B,therefore, is referred to as a polycyclic cis-endo 2,3-diol monomer. ForFormula C, R⁵ is depicted as extending upward out of the page and isexo-relative to the X group, R⁶ is depicted as extending downward intothe page and is therefore endo-relative to the X group; additionally, R⁵and R⁶ are trans-relative to one another. Formula C, therefore, isreferred to as a polycyclic endo/exo 2,3-diol monomer or a polycyclictrans 2,3-diol monomer.

Some of the polynorbornanediol carbonate embodiments as described abovecan encompass repeating units derived from polycyclic 2,3-diols selectedfrom each of Formulae A, B and C or selected from any one or two of suchformulae.

When such a polynorbornanediol carbonate embodiment encompassesrepeating units derived from two polycyclic 2,3-diol monomersrepresented by and selected from Formulae A, B and C, such embodimentswill be understood to include mole percent ratios where any single molepercent is 1 and where any other single mole percent is 99. For example,the mole percent ratio of such repeating units include, but are notlimited to 1 to 99, 10 to 90, 30 to 70, or any other subratio subsumedtherein provided that the sum of the mole percents of such repeatingunits is 100 mole percent.

Some of the polynorbornanediol carbonate embodiments of the presentinvention encompass monomers represented by and selected from each ofFormula A, Formula B and Formula C. Such embodiments will be understoodto include mole percent ratios where any single mole percent is 1 andwhere any other single mole percent is 98. For example, such molepercent ratios including, but are not limited to 1 to 1 to 98, 10 to 10to 80, and 33.33 to 33.33 to 33.33, or any other subratio subsumedtherein, provided that the sum of the mole percents is 100 mole percent.

Therefore, it will be understood that the polynorbornanediol carbonateembodiments in accordance with the present invention can encompassrepeating units of any one, two or three of the above described monomersrepresented by Formulae A, B and C. Further, it will be understood thatR⁵ and R⁶ can be independently selected from —(CH₂)_(p)—OH, where p is0, 1, 2 or 3. In some embodiments of the present invention, the sum ofthe p for R⁵ and p for R⁶ is either 1 or 3.

Still further, it will be understood that for any of the aforementionedpolynorbornanediol carbonate embodiments of the present invention, atleast one of R¹-R⁴ of any one or more repeat units encompassed thereinis a group independently selected from alkyl, cycloalkyl, heteroalkyl,heterocycloalkyl, aryl, heteroaryl and aralkyl, and the others of R¹-R⁴,if any, that are not selected from such non-hydrogen groups, are eachhydrogen. Examples of alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl,aryl, heteroaryl and aralkyl groups from which each of R¹-R⁴ can beselected include, but are not limited to, those classes and examples asrecited previously herein, which can optionally include one or morefurther substituents, such as, but not limited to: halohydrocarbylsubstituents, such as but not limited to C₁-C₂₅ linear or branchedperfluoro alkyl groups, such as but not limited to, —CF₃; carboxylicacid esters, such as but not limited to —COOR′, where R′ is ahydrocarbyl group; and ether groups, such as but not limited to —OR″,where R″ is a hydrocarbyl group.

Further still, it will be understood that in some polynorbornanediolcarbonate embodiments in accordance with the present invention repeatingunits are derived from the monomers represented by Formulae A, B and C,where n is 0; X is methylene, three of R¹-R⁴, are each hydrogen; and oneof R¹-R⁴ is both independently selected from an alkyl, cycloalkyl,heteroalkyl, heterocycloalkyl, aryl, heteroaryl or aralkyl group, andoriented exo relative to X. For purposes of illustration, such monomerscan be represented by the following Formulae A1, B1 and C1.

Additionally, some polynorbornanediol carbonate embodiments inaccordance with the present invention, encompasses repeat units derivedfrom: (a) polycyclic 2,3-diol monomers represented by one or more ofFormulae A, A1, B, B1, C and/or C1; and (b) one or more further diolmonomers that are other than polycyclic 2,3-diol monomers represented byFormulae A, A1, B, B1, C and/or C1. Such further diol monomers, as willbe described further herein, include, but are not limited to: (i)polycyclic diol monomers represented by at least one of Formulae D, E, Fand G; (ii) cyclic diol monomers represented by at least one of FormulaeI-XII; (iii) polycyclic diol monomers represented by at least one ofFormulae XIIa-XIIc; (iv) further optional diol monomers, such ashydrocarbyls having two or more hydroxyl groups; and combinationsthereof.

Polynorbornanediol carbonate embodiments according to the presentinvention, encompass at least one repeat units derived from one or moreof the polycyclic 2,3-diol monomers (a) represented by Formulae A-G,A1-F1 and D1a-F1a disclosed above and below. Additionally suchpolynorbornanediol carbonates can encompass one or more other diols (b)such as those represented by Formulae I-XIIc, disclosed below. Any oneof the repeat units of such polycarbonates can be present in an amountof from 1 to 99 mole percent, or 5 to 95 mole percent, or 10 to 90 molepercent. The mole percents in each case being based on the total molesof repeating units derived from polycyclic 2,3-diol monomers (a), andother diols (b), provided that the sum of mole percents of repeatingunits is 100 mole percent.

Such other diols (b) can be used for purposes of modifying the physicalproperties of the resulting polycarbonate polymer. For example, suchother diols (b) can provide the resulting polycarbonate polymer withweak links, that render the polycarbonate polymer more susceptible todepolymerization in the presence of an appropriate acid or base.Alternatively, or in addition to providing weak links, such other diols(b) can modify the T_(g) and/or the solubility of the resultingpolycarbonate polymer.

Some polymer embodiments of the present invention include repeat unitsderived from polycyclic diol monomers represented by the followingFormulae D, E and F.

Independently for each further polycyclic diol monomer represented byFormulae D, E and F: m is 0, 1 or 2; Z and Z′ are each independentlyselected from —CH₂—, —CH₂—CH₂— and —O—; Z* is —CH—; R⁷, R⁸, R⁹ and R¹⁰are in each case independently selected from hydrogen, and a hydrocarbylgroup; R¹¹ and R¹² are in each case independently selected from—(CH₂)_(p)—OH, where p for R¹¹ and R¹² is in each case independentlyselected from 0, 1, 2 or 3; and each Z′ is, if present, oriented thesame or opposite the orientation of Z or Z*, respectively.

With Formulae D, E and F, each Z group and Z* group is depicted asextending upward out of the page. With Formula D, each Z′, if present,has an orientation, independently for each m, that is the same oropposite relative to the orientation of Z. With Formulae E and F, eachZ′, if present, has an orientation, independently for each m, that isthe same or opposite relative to the orientation of Z*.

The hydrocarbyl groups from which R⁷-R¹⁰ can each be independentlyselected include, but are not limited to, those classes and examplesrecited previously herein. For each of Formulae D-F, in embodiments ofthe present invention, at least one of R⁷-R¹⁰ is a group independentlyselected from an alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, aryl,heteroaryl and aralkyl group, and the other R⁷-R¹⁰ group(s), if any,that are not selected from such non-hydrogen groups, are each hydrogen.Examples of alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, aryl,heteroaryl and aralkyl groups from which each of R⁷-R¹⁰ can be selectedinclude, but are not limited to, those classes and examples as recitedpreviously herein with regard to R¹-R⁴.

In further embodiments, for each of Formulae D-F: m is 0; three ofR⁷-R¹⁰ are each hydrogen; and one of R⁷-R¹⁰ is independently selectedfrom alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, aryl, heteroaryland aralkyl, and is oriented exo relative to Z or Z*. For purposes ofillustration, with m=0, Z being —CH₂—, R⁷, R⁸ and R⁹ each beinghydrogen, R¹⁰ being a non-hydrogen exo group, R¹¹ and R¹² each being—CH₂OH for Formula D and —OH for Formulae E and F, Formulae D-F can berepresented by the following Formulae D1, E1 and F1. For purposes offurther illustration, with m=0, Z being —CH₂—, R⁸, R⁹ and R¹⁰ each beinghydrogen, R⁷ being a non-hydrogen exo group, R¹¹ and R¹² each being—CH₂OH for Formula D and —OH for Formulae E and F, Formulae D-F can berepresented by the following Formulae D1a, E1a and F1a. It will beunderstood, that unless specifically stated, all Formulae presentedherein are inclusive of the enantiomeric, and diastereomeric analogsthereof.

It should be noted that that Formulae D, D1 and D1a represent spiro diolmonomers in that each —(CH₂)_(p)—OH or —CH₂—OH group is covalentlybonded to the same carbon of the polycyclic structure.

Some other polymer embodiments in accordance with the present inventioninclude repeat units derived from polycyclic diol monomers representedby the following Formula G.

With the polycyclic diol represented by Formula G, Z, R¹¹ and R¹² areeach as described previously herein with regard to Formulae D-F.

Still other embodiments in accordance with the present invention canalso include polymers formed from cyclic and acyclic diol monomersrepresented by the following Formulae I through XII.

For Formulae X and XI, R¹³ is independently selected from C₁-C₆ alkyl,such as but not limited to methyl, ethyl and C₃-C₆ linear alkyl or C₃-C₆branched alkyl.

Additional polymer embodiments of the present invention include repeatunits derived from the polycyclic monomers represented by Formulae XIIa,XIIb and XIIc.

Still further polyol monomers useful for embodiments in accordance withthe present invention include, but are not limited to, hydrocarbylshaving two or more hydroxyl groups, such as but not limited to 2, 3 or 4hydroxyl groups. Examples of such further diol monomers include, but arenot limited to: methyl, ethyl, C₃-C₂₅ linear or branched alkylene diols,such as, 1,2-ethylenediol, 1,3-propylenediol and 1,2-propylenediol; andpolyalkyleneglycols, such as di-, tri-, tetra- and higherethyleneglycols, di-, tri, tetra- and higher propyleneglycols, andpolytetrahydrofuran. Optional polyol monomers having more than twohydroxyl groups are typically present in small amounts, such as but notlimited to less than 10 mole percent, or less than 5 mole percent, basedon the total mole percent of hydroxyl functional monomers. Examples ofpolyol monomers having more than two hydroxyl groups include, but arenot limited to, trimethylolpropane, pentaerythritol anddi-trimethylolpropane.

As previously mentioned, some embodiments in accordance with the presentinvention encompass commercially available alkylenecarbonate polymers(also referred to as polyalkylenecarbonates) that are not derived frompolyol monomers represented by any of the aforementioned formulae.Rather, such commercially available alkylenecarbonate polymers arerepresented by Formula M, shown below:

Where each R_(a) is independently hydrogen or an optionally substitutedgroup selected from the group consisting of a C₁ to C₃₀ aliphatic; C₁ toC₃₀ heteroaliphatic having 1-4 heteroatoms independently selected fromthe group consisting of nitrogen, oxygen, silicon and/or sulfur; 6- to10-membered aryl; 5- to 10-membered heteroaryl having 1-4 heteroatomsindependently selected from nitrogen, oxygen, silicon and/or sulfur; and3- to 7-membered heterocyclic having 1-3 heteroatoms independentlyselected from nitrogen, oxygen, silicon and/or sulfur; and each ofR_(b), R_(c) and R_(d) is independently hydrogen or an optionallysubstituted group selected from the group consisting of C₁ to C₁₂aliphatic; C₁ to C₁₂ heteroaliphatic having 1-4 heteroatomsindependently selected from the group consisting of nitrogen, oxygen,silicon and/or sulfur; 6- to 10-membered aryl; 5- to 10-memberedheteroaryl having 1-4 heteroatoms independently selected from nitrogen,oxygen, silicon and/or sulfur; and 3- to 7-membered heterocyclic having1-3 heteroatoms independently selected from the group consisting ofnitrogen, oxygen, silicon and/or sulfur; where any of (R_(a) and R_(c)).(R_(c) and R_(d)) and (R_(a) and R_(b)) can be taken together withintervening atoms to form one or more optionally substituted rings thatcan optionally contain one or more heteroatoms.

For non-limiting, illustrative purposes only, Synthetic Schemes 1-7 areprovided to demonstrate art-recognized methods for preparing the variouspolycyclic 2,3-diol monomers discussed above. Thus the polycycliccis-exo 2,3-diol monomer represented by Formula A can be prepared inaccordance with the following Synthetic Scheme 1, in which n is 0, R¹-R⁴are each hydrogen, X is —CH₂—, and R⁵ and R⁶ are each —CH₂OH.

With reference to Synthetic Scheme 1, endo-2,3-norbornene dicarboxylicacid anhydride (also referred to as endo-nadic anhydride) (1a) isexposed to a temperature of 140 to 210° C. for a sufficient period oftime, such as from 15 minutes after melting to 24 hours, followed byrepeated recrystallizations, such as 2 or more recrystallizations fromethyl acetate or toluene, so as to form5-norbornene-cis-exo-2,3-dicarboxylic acid anhydride (also referred toas exo-nadic anhydride) (1b). Hydrogenation of exo-nadic anhydride (1b)in the presence of hydrogen gas (H₂), palladium catalyst supported onporous carbon (Pd/C), and ethyl acetate (EtOAc), results in formation ofexo-2,3-norbornane dicarboxylic acid anhydride (1c). Reduction ofexo-2,3-norbornane dicarboxylic acid anhydride (1c) in the presence oflithium aluminum hydride (LIMN and ethyl ether (Et₂O) results information of cis-exo-2,3-norbornanedimethanol (A2).

The polycyclic cis-endo 2,3-diol monomer represented by Formula B can beprepared in accordance with the following Synthetic Scheme 2, in which nis 0, R¹-R⁴ are each hydrogen, X is —CH₂—, and R⁵ and R⁶ are each—CH₂OH.

With reference to Synthetic Scheme2,5-norbornene-cis-endo-2,3-dicarboxylic acid anhydride (also referredto as endo-nadic anhydride) (1a) is hydrogenated in the presence ofhydrogen gas (H₂), palladium catalyst supported on porous carbon (Pd/C),and ethyl acetate (EtOAc), results in formation of endo-2,3-norbornanedicarboxylic acid anhydride (2a). Reduction of endo-2,3-norbornanedicarboxylic acid anhydride (2a) in the presence of lithium aluminumhydride (LiAlH₄) and ethyl ether (Et₂O) results in formation ofcis-endo-2,3-norbornanedimethanol (B2).

The polycyclic trans-endo-exo-2,3-diol monomer represented by Formula Ccan be prepared in accordance with the following Synthetic Scheme 3,which is provided for purposes of non-limiting illustration, in which nis 0, R¹-R⁴ are each hydrogen, X is —CH₂—, and R⁵ and R⁶ are each—CH₂OH.

With reference to Synthetic Scheme 3, cyclopentadiene (3a) and diethylfumarate (3b) are reacted together by means of Diels-Alder reaction atreduced temperature, such as 0° C., so as to formtrans-endo-exo-2,3-norbornene bis(ethylcarboxylate) (3c). Hydrogenationof trans-endo-exo-2,3-norbornene bis(ethylcarboxylate) (3c) in thepresence of hydrogen gas (H₂), palladium catalyst on porous carbon(Pd/C), and ethyl acetate (EtOAc), results in formation oftrans-endo-exo-2,3-norbornane bis(ethylcarboxylate) (3d). Reduction oftrans-endo-exo-2,3-norbornane bis(ethylcarboxylate) (3d) in the presenceof lithium aluminum hydride (LiAlH₄) and ethyl ether (Et₂O) results information of trans-exo-endo-2,3-norbornanedimethanol (C2).

The polycyclic cis-exo-2,3-diol monomer represented by Formula A can beprepared in accordance with the following Synthetic Scheme 4, which isprovided for purposes of non-limiting illustration, in which n is 0,R¹-R⁴ are each hydrogen, X is —CH₂—, R⁵ is —OH and R⁶ is —CH₂OH.

With reference to Synthetic Scheme 4,hexahydro-4H-5,8-methanobenzo[d]-exo-[1,3]dioxane (4a) is converted tocis-exo-(3-acetoxynorborn-2-yl)methyl acetate (4b) andcis-exo-((3-acetoxynorborn-2-yl)methoxy)methyl acetate (4c) in thepresence of acetic anhydride (Ac₂O) and a catalytic amount of sulfuricacid (H₂SO₄). The intermediates (4a) and (4b) are converted tocis-exo-3-(hydroxymethyl)norbornan-2-yl (A3) in the presence of waterand a catalytic amount of sodium hydroxide (NaOH).

The polycyclic cis-endo-2,3-diol monomer represented by Formula B can beprepared in accordance with the following Synthetic Scheme 5, which isprovided for purposes of non-limiting illustration, in which n is 0,R¹-R⁴ are each hydrogen, X is —CH₂—, R⁵ is —OH and R⁶ is —CH₂OH.

With reference to Synthetic Scheme 5,hexahydro-4H-5,8-methanobenzo[d]-endo-[1,3]dioxane (5a) is converted tocis-endo-(3-acetoxynorborn-2-yl)methyl acetate (5b) andcis-endo-((3-acetoxynorborn-2-yl)methoxy)methyl acetate (5c) in thepresence of acetic anhydride (Ac₂O) and a catalytic amount of sulfuricacid (H₂SO₄). The intermediates (5a) and (5b) are converted tocis-endo-3-(hydroxymethyl)norbornan-2-yl (B3) in the presence of waterand a catalytic amount of sodium hydroxide (NaOH).

The optional polycyclic diols represented by Formulae D, E, F and G canbe prepared by art-recognized methods. For purposes of non-limitingillustration, the optional polycyclic diol represented by Formula F canbe synthesized in accordance with the following Synthetic Scheme 6,where m is 0, R⁷-R¹⁰ are each hydrogen, Z is —CH₂—, R¹¹ is —OH and R¹²is —CH₂OH.

With reference to Synthetic Scheme 6,2,3-norbornene (6a) is converted to(2-(formyloxy)norborn-7-yl)-exo-methyl formate (6b) in the presence offormic acid (HCOOH) sulfuric acid (H₂SO₄) and formaldehyde (H₂CO).Intermediate (6b) is then converted to7-(hydroxymethyl)norbornan-2-exo-ol (F1) in the presence of sodiumhydroxide (NaOH) and methanol (MeOH).

Alkylenecarbonate polymer embodiments according to the present inventioncan also be prepared by art-recognized methods. For example, thealkylenecarbonate polymers according to embodiments of the presentinvention can be prepared by a carbonyl halide route, in which one ormore polycyclic 2,3-diol monomers are reacted with a carbonyl halide,X₂C═O, in which each X is selected independently from a halo group. Anexample of a carbonyl halide includes, but is not limited to, phosgene,where each X is chloro (Cl). Alternatively, a carbonyl diimidazole routecan be used, in which one or more polycyclic 2,3-diol monomers arereacted with N,N-carbonyldiimidazole.

Typically, polymer embodiments prepared from the aforementioned diolmonomers are polymerized via a carbonate route in which one or morepolycyclic 2,3-diol monomers are reacted with a dialkyl carbonate, suchas diethyl carbonate, a diaryl carbonate, such as diphenyl carbonate,and/or an alkyl-aryl carbonate. For purposes of non-limitingillustration of embodiments in accordance with the present invention, apolycarbonate polymer can be prepared in accordance with the followingSynthetic Scheme 7.

With reference to Synthetic Scheme 7, cis-exo-2,3-norbornanedimethanolmonomer (A2) is reacted with diphenyl carbonate (7a) in the presence ofsodium carbonate, which results in formation ofpoly(cis-exo-2,3-norbornane dimethyl carbonate) (7b), in which y is thenumber of repeat units. The cis-exo-2,3-norbornanedimethanol monomer(A2), is a polycyclic 2,3-diol monomer according to Formula A, in whichn is 0, R¹-R⁴ are each hydrogen, X is —CH₂—, and R⁵ and R⁶ are each—CH₂OH.

For polycarbonate polymer embodiments according to the presentinvention, the polycarbonates can be selected from homopolymers, such ashomopolymers containing a single type of repeating unit derived from oneof Formulae A, B or C, or random copolymers, or block copolymers, oralternating copolymers, which are alternatively referred to herein asrandom polymers, block polymers and alternating polymers. The random,block and alternating polycarbonate copolymer embodiments according tothe present invention can include two or more types of repeating unitsderived from at least one of Formulae A, B or C.

For some embodiments according to the present invention, thepolycarbonates can have a wide range of molecular weights. For example,such polymers can have weight average molecular weight (M_(w)) values offrom 2000 to 250,000, or from 8000 to 150,000, or from 9000 to 80,000;and polydispersity index (PDI) values (M_(w)/M_(n)) of greater than 1.0and less than or equal to 4.0, such as, but without limitation, from 1.1to 4.0, or from 1.2 to 2.0, or from 1.3 to 1.8.

For some embodiments according to the present invention, thepolycarbonates can have a wide range of glass transition temperature(T_(g)) values, such as but not limited to, Tg values of from −50° C. to200° C., or from 25° C. to 180° C., or from 60° C. to 175° C.

For some embodiments according to the present invention, thepolycarbonates can be characterized with regard to the temperature atwhich the polymer decomposes, which can also be referred to as adecomposition temperature. For some embodiments, the decompositiontemperature of the polycarbonates can be quantified with regard to theirhalf-decomposition temperature (T_(d50)), which is the temperature atwhich a 50 percent weight loss is observed. Half-decompositiontemperatures are typically determined by means of thermogravimetricanalysis (TGA). Half-decomposition temperatures can be determined forthe polymer alone and for the polymer in the presence of additives,e.g., a thermally activated base generator after its activation.

Embodiments in accordance with the present invention also providesacrificial polymer compositions that encompass: a single type ofpolycarbonate having one or more types of carbonate repeat units asdescribed previously herein and a thermally activated base generator.The sacrificial polymer composition embodiments according to the presentinvention, can also encompass a single type of polycarbonate or a blendor mixture of two or more types of polycarbonates.

For embodiments of the present invention, where the sacrificial polymercomposition encompasses a single polycarbonate, such polymer canencompass any of the previously mentioned polyalkylenecarbonates or bederived from polycyclic 2,3-diol monomers as described above and below.Where such polymer composition embodiments encompass two or more typesof polymers, each of such polymers can be two or more distinctpolyalkylenecarbonates or two or more polymers derived from distinctpolycyclic 2,3-diol monomers. Thus the sacrificial polymer compositionembodiments in accordance with the present invention can encompass justa first polycarbonate having repeating units derived from polycyclic2,3-diol monomers represented by one or both of Formulae A and B; or acombination of such first polycarbonate and a second polycarbonatehaving repeating units derived from polycyclic 2,3-diol monomersrepresented by Formula C. Additionally, such sacrificial polymerembodiments can encompass one or more of the aforementioned commerciallyavailable polyalkylene carbonates.

The thermally activated base generator used in the sacrificialcomposition embodiments in accordance with the present invention,generates a base upon heating to an effective temperature, where thegenerated base causes depolymerization of the sacrificial polymer. Asused herein, the term “depolymerization” will be understood to mean thatthe sacrificial polymer is at least partially broken down into smallerunits each having a molecular weight less than the molecular weight ofthe polymer prior to depolymerization. Such depolymerized units include,but are not limited to: the monomers from which the polymer was derived;polycarbonate oligomers; hydroxyl-terminated polycyclic carbonateoligomers; polycyclic carbonates; polycyclic ethers; cyclic carbonates,CO and/or CO₂.

For purposes of nonlimiting illustration, the depolymerization of apolycarbonate or polycarbonate segment derived from a polycyclic2,3-diol represented by Formula A, in which n is 0, X is —CH₂—, andR₁-R₄ are each hydrogen, so as to form polycyclic carbonates containingat least one carbonate linkage in the polycyclic ring, and/or polycyclicethers containing at least one ether linkage in the polycyclic ring, andthe depolymerization of a commercially available polypropylene carbonateare represented by the following Schemes 8a and 8b.

The polycyclic carbonates and/or polycyclic ethers depicted in Schemes8a and 8b are vaporized by concurrent or subsequent application ofelevated temperature. For some embodiments of the present invention, themoieties created by the depolymerization, such as polycyclic carbonatesand/or polycyclic ethers, permeate through an overcoat layer, as will bedescribed in further detail herein.

For some embodiments of the present invention, the polycarbonate polymercan encompass one or more monomer units derived from polycyclic diolmonomer D. At least partial depolymerization of such polycarbonatepolymers in the presence of a base, activated with an elevatedtemperature, can result in the formation of one or more polycycliccarbonate and/or polycyclic ether depolymerization units represented bythe following Formulae D-DU1 and D-DU2, respectively.

With some embodiments, for each of Formulae D-DU1 and D-DU2, at leastone p is at least 1. Vaporized depolymerization units represented byFormulae D-DU1 and D-DU2 can permeate through an overcoat layer, as willbe described in further detail herein.

The thermally activated base generators (TABG), described below, areencompassed in polymer composition embodiments of the present invention.Such TABGs include, but are not limited to, bases encompassing cationsrepresented by any of Formulae 1, 2 or 3:

where each R¹ is independently selected from hydrogen, a methyl or ethylgroup, a linear, branched or cyclic C₃-C₁₂ alkyl group; a linear,branched or cyclic C₃-C₁₂ heteroalkyl group having from 1 to 4heteroatoms independently selected from nitrogen, oxygen or sulfur; aC₆-C₁₀ aryl group; a C₅-C₁₀ heteroaryl group having from 1 to 4heteroatoms independently selected from nitrogen, oxygen or sulfur; orwhere two R¹ groups are taken together with any intervening atoms toform one or more cyclic alkyl or heteroalkyl groups as previouslydefined, and where for Formula 1, at least one R¹ is hydrogen. Exemplarytetra-alkyl bases include, among others, tetra-ethyl amine (Et₄N⁺) andtetra-butyl amine (Bu₄N⁺). The former being available as an acetate saltfrom Aldrich Specialty Chemicals as Catalog Number 205583 and from Flukaas Catalog Number 96607. The latter also being available from eitherAldrich or Fluka as Catalog Numbers 335991 and 86835, respectively. Aswill be seen in the Examples, a proprietary amidine salt, CXC-1761,available from King Industries, was also evaluated as a TABG.

The thermally activated base generators in accordance with the presentinvention are salts generally having a carboxylate anion. Such saltsbeing characterized by releasing a free base when heated to an effectiveactivation temperature, the free base then having sufficient basicity tocause depolymerization as shown in Scheme 8b. Referring now to Table A(derived from the Thesis of Xun Sun, entitled “Development oftetraphenylborate-based Photobase generators and sacrificialPolycarbonates for radiation curing and Photoresist applications”;Carleton University, Ottawa, Ontario, November 2008), below, thebasicity of the released free bases 1,8-diazabicyclo[5.4.0]undec-7-ene(DBU), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), expressed as pK_(a)measured in acetonitrile, are at least 24.34 and both exhibitsignificant reduction of the decomposition temperature (T_(d)) of apolypropylene carbonate. In contrast, the tertiary amines (TEA) andphenylhydrazine (PhNHNH₂), with pK_(a) 12.33 or less, exhibited only asmall reduction in T_(d). Thus this reduction in PPC decompositiontemperature is a measure of both basicity and the effectiveness of aspecific TABG and can be employed to screen potential TABGs.

TABLE A Bases pK_(a) ΔT_(d) Residuals (wt %) TBD 25.03 175 0.3 DBU 24.3480 0.7 TEA 18.8 10 0.9 PhNHNH₂ 12.33 10 4.8

Based on the aforementioned pK_(a) values, thermally generated basesuseful for embodiments in accordance with the present inventionencompass one or more of the following structures.

Representative structures of carboxylates, in their acid form, useful asthe carboxylate anion of the TABG embodiments of the present inventionare depicted below:

Exemplary TABG structures can then be shown as:

The amount of TABG useful in composition embodiments in accordance withthe present invention is any amount that generates an effective amountof base to catalyze the depolymerization reaction, such amount can thusbe referred to as an effective amount. For some embodiments, such amountis from 0.1 to 25 pphr inclusive, based on the weight of the polymer; inother embodiments from 0.5 to 15 pphr inclusive and in still otherembodiments, from 1 to 12 pphr inclusive. It will be understood, thatfor some embodiments of the present invention, it can be advantageous toemploy a mixture of TABGs where the effective amount of such mixture isinclusive of the ranges expressed above. Further, some polymercomposition embodiments in accordance with the present inventionencompass a mixture of a TABG and an effective amount of formic acid.

For some embodiments according to the present invention, the sacrificialpolymer composition can further include one or more solvents. Solventcan be present in an amount of from, for example, 10 to 99 percent byweight, or 40 to 90 percent by weight, or 50 percent to 80 percent byweight, based on the total weight of the sacrificial polymercomposition. Examples of solvents that can be included in thesacrificial polymer composition include, but are not limited to,acetonitrile, acetophenone, α-angelicalactone, anisole, γ-butyrolactone,n-butyl acetate, cyclohexylbenzene, cyclohexanone, cyclopentanone,decahydronaphthalene, diethylene glycol dimethyl ether,N,N-dimethylacetamide, N,N-dimethylformamide, ethyl 3-ethoxypropionate,ethyl lactate, 2-heptanone, methyl isobutyl ketone, mesitylene,2-methoxyethyl ether, 1-methyl-2-pyrrolidinone, 2-methyltetrahydrofuran,methyl tetrahydrofurfuryl ether, γ-octanoic lactone, propylenecarbonate, propylene glycol monomethyl ether acetate, propylene glycolmonomethyl ether, 1,2,3,4-tetrahydronaphthalene, and combinationsthereof.

As discussed previously herein with regard to polycarbonate embodimentsof the present invention, sacrificial polymer composition embodimentsaccording to the present invention can be characterized with regard tothe temperature at which the composition decomposes or depolymerizes,which can be referred to as a decomposition temperature of thesacrificial polymer composition. The decomposition temperature of thesacrificial polymer composition can be quantified with regard to theT_(d50) decomposition temperatures as described previously herein.

In further accordance with embodiments of the present invention, thereis also provided methods of forming useful microelectronic oroptoelectronic devices or structures that make use of the aforementionedsacrificial polymer composition embodiments of the present invention.

Referring first to the forming of such devices, some such device formingembodiments in accordance to the present invention encompass providing afirst and a second substrate where each substrate has a surface thatencompasses a plurality of first and second metal bumps or contactstructures, respectively. It will be understood that each of the firstand second substrates can be a microelectronic device such as asemiconductor chip or die so that a chip stack is formed, or that one ofsuch substrates is a semiconductor chip and the other a substrate suchas would be employed in forming a “flip-chip” assembly. Further, it willbe understood that the aforementioned sacrificial polymer compositionembodiments of the present invention is applied to one or both of thesubstrates and that such substrates are positioned and held to oneanother by the tack properties of such composition, where each of theaforementioned plurality of metal bumps, or structures, areappropriately aligned and held in such alignment by the tackiness ofsuch sacrificial polymer composition such that electrical coupling canbe subsequently made. Still further it will be understood that at leastone of said first or second plurality of metal bumps encompasses soldersuch that upon heating the substrates and polymer composition to aneffective temperature, the solder will reflow to provide theaforementioned electrical coupling while the polymer compositionprovides a fluxing property to enable or enhance such electrical soldercoupling. Further still, it will be understood that the substrates andpolymer composition will be held at such effective temperature for atime sufficient to complete the electrical coupling and to allow for thedecomposition of the alkylenecarbonate polymer encompassed in thepolymer composition. It should be noted, that where the plurality offirst and second metal bumps, or structures, mentioned above, suchcharacterization is non-limiting and that some embodiments of thepresent invention can be characterized as having a plurality of firstand second metallic contacts (or contact regions), where at least one ofsuch pluralities encompasses solder or another bondable material.

With respect to the method described above, the application of polymercomposition embodiments can be accomplished by any suitable means. Forexample, printing, such as but not limited to, jet printing, which issimilar to inkjet printing, or screen printing; dispensing, such as butnot limited to, spot or line dispensing, spray coating, doctor bladingor spin coating.

With regard to the aforementioned effective temperature, suchtemperature will vary, at least, as a function of the specific TABGemployed. Additionally such temperature can be a function of the use ofthe polymer composition within which it is encompassed and the structurethat is being formed. For example, where a “flip-chip” structure isbeing made, such effective temperature is generally consistent with thereflow temperature of the solder, or other bondable material, selectedfor the electrical coupling. Whereas when a three-dimensional structureis being made, such effective temperature is a temperature less than thedecomposition temperature of the overcoat layer. Still further, theeffective temperature is also a function of the depolymerizationtemperature of the polycarbonate embodiment selected and the temperatureat which the depolymerization products are removed. Therefore, someforming embodiments in accordance with the present invention canencompass a first effective temperature to activate the base generatorand a second effective temperature to facilitate the removal ofdepolymerization products. Further still, the period of time whereheating to an effective temperature is maintained can also vary as afunction of the structure being formed, three-dimensional structurestypically requiring more time at the effective temperature than“flip-chip” type structures, as well as the amount of the polymercomposition used for such structure or device forming method.Advantageously, for embodiments according to the present invention, boththe aforementioned three-dimensional space and the area between theelectrically coupled substrates are essentially free of residue of thesacrificial polymer composition.

While it will be seen in the Examples provided below, that the polymercomposition embodiments in accordance with the present invention areeffective tack and flux agents, such embodiments can also be employedfor temporarily bonding a first substrate to a second substrate. Suchbonding forming a multilayered structure that includes a firstsubstrate, a second substrate, and a temporary bonding layer interposedbetween the first substrate and the second substrate. The temporarybonding layer, alternatively be referred to as a temporary adhesivelayer, being formed from such a polymer composition embodiment. Further,it will be realized that such a multilayer structure is useful toprovide a substrate surface for a process such as chemical mechanicalpolishing or the creation of through silicon vias (TSVs). When the TABGis activated, the sacrificial polymer is at least partiallydepolymerized allowing for the substrates to be debonded or separatedfrom one another.

Still further, the polymer composition embodiments in accordance withthe present invention can be used in or in conjunction with still otherapplications where either a temporary or permanent bond is useful. Suchapplications including, but not limited to, applications in the field ofmicroelectronics, such as but not limited to, flip-chip structures,microprocessor chips, communication chips, and optoelectronic chips; andthe fields of microfluidics; sensors; and analytical devices, such asbut not limited to, microchromatographic devices.

The following examples are for illustrative purposes and are notintended to limit the scope of embodiments in accordance with thepresent invention in any way. It will be noted that the ratios ofrepeating units incorporated into the polymer backbones are given inmolar weight percent.

EXAMPLES

Polynorbornanediol carbonates according to embodiments of the presentinvention were prepared in accordance with the synthetic proceduresdescribed in the following Examples 1-5. Properties of the carbonatesformed in the manner of Examples 1-3 are summarized in Tables 1a and 1b,below. In these tables, T_(g) values were determined by differentialscanning calorimetry at a heating rate of 10° C./minute; the T_(d5),T_(d50) and T_(d95) values were determined by thermogravimetric analysisat a heating rate of 10° C./minute, and indicate the temperatures atwhich 5 percent, 50 percent and 95 percent by weight of the polymer haddecomposed; the chain-end phenyl group (End Ph) percent mole valuesindicate the theoretical amount of phenol, based on the initial amountof diphenyl carbonate raw material charged, that was not removed duringpolymerization; the mole percents were determined by ¹H NMR analysis,and indicate the percent of monomer units in the polymers derived fromthe particular cis-exo- or cis-endo-2,3-norbornanedimethanol monomer,the remainder corresponds to the percent of monomer units in thecopolymer derived from the other monomer: 41%cis-endo-2,3-norbornanedimethanol (Example 1); 59% 1,3-cyclohexanediol(Example 2); and 59% 1,3-cyclohexanediol (Example 3); solubility wasdetermined by attempting to dissolve a target resin content (RC, 20 wt%) of the polymer in a process solvent, the designation “A” refers toanisole, and the designation “G” refers to γ-butyrolactone.

Polycarbonate Polymer Examples Example 1

The following were added to a suitably sized and outfitted multi-neckedflask, including, for example, a thermocouple, heating mantle,mechanical stirrer, nitrogen sweep, and vacuum pump: 22.5 grams ofcis-exo-2,3-norbornanedimethanol (144 millimoles or mmoles); 15.0 gramsof cis-endo-2,3-norbornanedimethanol (96 mmoles); 51.3 grams of diphenylcarbonate (240 mmoles); and 12 milligrams (mg) of lithium hydride (1.5mmoles). The contents of the flask were heated to and held at 120° C.under a nitrogen sweep for a period of time sufficient to convert thecontents thereof to a liquid. The contents of the flask were then heldat 120° C. for 2 hours with constant stirring and under a nitrogensweep. The contents of the flask were then subjected to a reducedpressure of about 10 kPa, with constant stirring at 120° C. for 1 hour.The pressure within the flask was then further reduced to less than 0.5kPa, and the contents subjected to continued stirring at 120° C. for 1.5hours, followed by a 1.5 hour hold at 180° C.

The contents of the flask were cooled and dissolved in a suitable amountof tetrahydrofuran, such as 800 ml, and filtered. The filtered solutionwas then added to and precipitated from an appropriate amount, such as 8liters, of a liquid including methanol and distilled water in a volumeratio 9 to 1. The precipitated polymer was washed with an appropriateamount, such as 4 liters, of wash liquid including methanol anddistilled water in a volume ratio 9 to 1, and then dried. About 30.7grams of polycarbonate copolymer were obtained in a yield of about 70percent. The polycarbonate copolymer was determined by gel permeationchromatograph (GPC) to have a weight average molecular weight (M_(w)) of41,000, and a polydispersity index (PDI) of 1.70.

Example 2

A polycarbonate copolymer according to embodiments of the presentinvention was prepared in accordance with the procedure described inExample 1 from the following: 20.5 grams of 1,3-cyclohexanediol (176mmoles); 15.5 grams of cis-exo-2,3-norbornanedimethanol (99 mmoles);56.6 grams of diphenyl carbonate (264 mmoles); and 13.2 mg of lithiumhydride (1.7 mmoles). About 28.1 grams of polycarbonate copolymer wereobtained in a yield of about 69 percent. The polycarbonate copolymer wasdetermined by GPC to have a M_(w) of 47,000, and a PDI of 1.75.

Example 3

A polycarbonate copolymer according to embodiments of the presentinvention was prepared in accordance with the procedure described inExample 1 from the following: 19.2 grams of 1,3-cyclohexanediol (165mmoles); 14.5 grams of cis-endo-2,3-norbornanedimethanol (93 mmoles); 53grams of diphenyl carbonate (248 mmoles); and 10.1 mg of lithium hydride(1.3 mmoles). About 28.7 grams of polycarbonate copolymer were obtainedin a yield of about 76 percent. The polycarbonate copolymer wasdetermined by GPC to have a M_(w) of 38,000, and a PDI of 1.61.

TABLE 1 T_(g) T_(d5) T_(d50) Example % Yield M_(w) M_(w)/M_(n) (° C.) (°C.) (° C.) (1) 70 41,000 1.70 89 279 291 (2) 68 47,000 1.75 112 262 285(3) 74 38,000 1.61 117 269 293

TABLE 2 Exam- End ple T_(d95) (° C.) Ph (%) Mole % Solubility @ RC = 20%(1) 298 10 exo = 59 A: soluble G: Insoluble (2) 309 18 exo = 41 A:soluble G: soluble (3) 315 17 endo = 41 A: soluble G: soluble

Example 4

An appropriately sized reaction vessel equipped with a stir bar wascharged with 10.0 g (43 mmol) of 5-exo-phenyl-cis-exo-2,3-norbornanedimethanol and 9.2 g (43 mmol) of diphenyl carbonate and 1.3 mg (0.16mmol) of lithium hydride. A condensing arm was assembled, fitted to thereaction vessel and the vessel and condenser evacuated and refilled withnitrogen three times. The reaction flask was heated with stirring at120° C. oil-bath temperature under nitrogen for 2 hours. The nitrogensource was removed, and the reaction was subjected to a partial vacuumof 75 Torr at 120° C. for 1 hour and allowed to cool to roomtemperature. The polymer solution in a mixture of methylene chloride andtetrahydrofuran was dropwise added to pure methanol duringprecipitation. After filtration and drying in a dynamic vacuum oven, 9.1g white polymer was obtained. Polymer properties are summarized asfollow: M_(w)=49 k, PDI=2.0, T_(g)=115° C., T_(d50)=284° C.

Example 5

With setup and handling procedures similar to Example 4, the monomersused in this experiment are 5.0 g (22 mmol) of5-exo-phenyl-cis-endo-2,3-norbornane dimethanol and 4.6 g (22 mmol) ofdiphenyl carbonate. The catalyst lithium hydride used is 0.9 mg (0.11mmol). Polymer solution in a mixture of methylene chloride andtetrahydrofuran was dropwise added to pure methanol duringprecipitation. After filtration and drying in a dynamic vacuum oven, 4.7g white polymer was obtained. Polymer properties are summarized asfollow: M_(w)=38 k, PDI=2.1, T_(g)=111° C., T_(d50)=314° C.

The photochemical decarboxylation mechanism of ketoprofen salts is knownin photobase generators with protonated cations of DBU or DBN (SeeJournal of Photopolymer Science and Technology 2010, 23(1), 135-136 andJournal of Photopolymer Science and Technology 2009, 22(5), 663-666).While the concept in generation of a base (e.g., an amine) byphotochemical decarboxylation has been well established for over 20years (see Journal of Photopolymer Science and Technology 1990, 3(3),419-422 and U.S. Pat. No. 5,545,509), it is equally known in the artthat some molecules will not undergo spontaneous thermal decarboxylation(see Journal of Photopolymer Science and Technology 2006, 19(6), 683-684and Journal of Photopolymer Science and Technology 1999, 12(2),315-316). Observation of structures 1 and 2 in Equation 1 was confirmedby chemical ionization as PT-393 was heated in the absence ofultra-violet light, suggesting that a similar thermal decarboxylationprocess also takes place. As carbon dioxide is formed from thecarboxylate group, a hydrogen is abstracted from the cation, thusreleasing a base 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD, 2) in-situduring reflow.

Since the base 2 is only generated from PT-393 upon heating, the roomtemperature polymer formulation of PT-393 is stable for at least onemonth. It does not contain free acid or free base, and is anon-corrosive formulation. The strong base generated upon reflow servesas the solder flux agent by removing oxide or contaminants from themetal surface. The strong base also initiates base-catalyzed chainscission and unzipping of the polycarbonate (Scheme 8b) part of thecomposition initially used in fixturing the solder components. Thecyclic species generated from the polymer are volatile and will vaporizetogether with the carrier solvent under typical reflow conditionsat >230° C. Typical carrier solvents such as γ-butyrolactone, anisole,and cyclopentanone have boiling points below 210° C. PT-393 shows theprofile of a latent additive in TGA with 5% weight loss temperature(T_(d5)) at 229° C. and is expected to be fully removed under reflow.

Example 6 Preparation of PT-393

2-(3-Benzoylphenyl)propanoic acid (ketoprofen, 8.00 g, 31.5 mmol) wasdissolved in THF (100 mL) with magnetic stirring at room temperature.1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD, 4.38 g, 31.5 mmol) was slowlyadded as a dry powder to the clear THF solution—the temperature increaseduring this addition is minimal at the current level of dilution. Theheterogeneous mixture was stirred vigorously at room temperature for 12h, the turbidity gradually decreased over this period. The reactionmixture was filtered through Celite® filtering aid on a glass frit andthe filtrate was concentrated to a viscous oil by rotary evaporation.Diethyl ether (15 mL) was added to the oily material and stirred for 30min to remove unreacted ketoprofen and TBD. The top layer was removedwith a Pasteur pipet and the ether wash was repeated twice. Thesupernatant from the last wash was kept in a closed vial at roomtemperature overnight and white crystals in mg scale are formed. Thewhite crystals give ¹H NMR similar to the crude mixture, and werecollected as seeds for subsequent bulk crystallization. THF (30 mL) wasadded to the washed bulk material and swirled until homogeneous. Diethylether was dropwise added to the THF solution until the end point whereone additional drop of ether will give a turbid solution even afterswirling. A few seed crystals were added to the clear THF/ether mixtureat the end point. After 4 h at room temperature, a layer of small whitecrystals was formed on the bottom glass surface. The mixture was kept ina refrigerator for 18 h. The white crystalline material was collected byfiltration on a glass frit, and washed with 2×5 mL diethyl ether. Thewhite solid was dried under oil-pump vacuum (≦0.1 Torr) for at least 12h to remove residual traces of solvent and give 8.5 g (69%) white solid,which is confirmed as the desired product PT-393 by ¹H NMR.

Example 7 Synthesis of exo-exo-2,3-Norbornanedicarboxylate Anhydride

Exo-,exo-2,3-norbornenedicarboxylate anhydride (94.4%, 634.23 g, 3.87mol) was split into ˜210 g portions and each dissolved via sonicationand heat in 1.5-1.7 L ethyl acetate. Each portion was added to the 19 LParr reactor and was followed with 3×400 mL ethyl acetate rinses. Totalethyl acetate used was 5.9 L. The Parr reactor had been pre-warmed to30° C. to prevent recrystallization of the anhydride. 5% Pd/C (50% wet,21.48 g) was added. The reactor was sealed and then pressurized withnitrogen three times. Then it was pressurized and flushed with hydrogenthree times. The reactor was finally pressurized to 108 psi hydrogen andstirred at 230 rpm. After 19 min, the mixture was recharged from 17 to105 psi. After 4 minutes, the reaction stabilized at 100 psi hydrogen.The mixture was allowed to stir at 100 to 86 psi and 26-31° C.overnight. NMR analysis revealed no more olefin remained. Four liters ofdichloromethane was added to the reaction mixture. The reactor wasdrained and then rinsed with 3×2000 ml portions of dichloromethane. Thereaction mixture and rinses were filtered through Celite to give aPd/C-free clear filtrate. The filtrate was rotary evaporated at 20-70°C. to give 639 g hard solid (99.5% yield). GC analysis revealed 98.7%exo isomer and 0.9% endo isomer for 99.6% total isomer purity.

Example 8 Synthesis of exo-,exo-2,3-Norbornanedimethanol

Lithium aluminum hydride pellets (192.7 g, 5.08 mol) were added to 4000ml anhydrous ether in a 4-neck 12 L flask fitted with mechanicalstirrer, addition funnel, condenser with nitrogen inlet, and thermowell.The mixture was stirred overnight. Exo,exo-2,3-norbornanedicarboxylateanhydride (330.3 g) was dissolved in 850 ml DrySolve THF and addeddropwise to the LAH slurry. Addition rate was adjusted to maintain agentle reflux (up to 35° C.). When addition was complete, the additionfunnel was recharged with 303.3 g exo-,exo-2,3-norbornanedicarboxylateanhydride in 1000 ml DrySolve THF. The fresh solution was added dropwiseto maintain a gentle reflux (40.1° C.). Totalexo,exo-2,3-norbornenedicarboxylate anhydride added was 633.6 g (3.81mol). Total addition time was 11 hrs. GC analysis revealed 95%conversion with no unreacted starting material detected. The mixture wasstirred overnight at room temperature. GC analysis showed 95.9%conversion. The reaction mixture was chilled to −12.4° C. and then 835ml water was added dropwise. After 80 ml water had been added, theexotherm subsided and the remaining water was added quickly. Theaddition was complete after 2 h 20 min with the temperature ranging from−12.4° C. to +12.4° C. 1.25 L MTBE (methyl tert-butyl ether) was added.Then 1.05 L 10% aqueous H₂SO₄ was added to coagulate and separate thelithium and aluminum salts. The ether-THF-MTBE phase was decanted andwashed with 2×1 L brine to remove carry-over solids and to bring the pHto 7. The ether solution was dried over sodium sulfate, filtered, androtary evaporated to give 355.4 (60% yield) of oil. GC analysis showed97.0% of the dimethanol (8.490 min retention time) and 2.3% unknowncomponent at 6.16 min retention time.

Separation of the organic phase from the brine phase was obscured by thesuspended solids. The brine washes were added back to the reactor tofluidize the remaining salts. The reactor flask was then rinsed withMTBE, which was added and thoroughly mixed with the brine mixture. Nophase separation occurred. The brine mixture was filtered to remove thelithium and aluminum salts. This gave a clean separation of ˜1000 mlorganic phase from the brine phase. The organic phase was dried oversodium sulfate, filtered, and rotary evaporated to give 149.9 g of thedimethanol. GC analysis showed 89.6% purity with major impurities of2.7% and 5.3% at 6.134 and 7.222 min retention time respectively.

The solid-free brine solutions were extracted with 400 ml and 800 mlMTBE. The MTBE extracts were dried over sodium sulfate, filtered, androtary evaporated to give 25.8 of 92.1% of the dimethanol with 1.1%6.144 min. retention time impurity and 6.6% 7.279 minute impurity.

The lithium and aluminum salts were washed with 2 L MTBE. The MTBEextract was washed with brine to pH 7, then dried over sodium sulfate,decanted, and rotary evaporated to 22.1 g 93% of the dimethanol. Thissample had 2.1% and 15.1% impurities at 6.136 and 7.269 minutesrespectively. These last three extracts were combined for a total of197.8 g and kept distinct from the primary extract of 355.4 g.

The 355 g extract was vacuum distilled through a 12-inch Vigreux columnwhere Fractions 4 through 7 were combined to give 120 g of product with99.0% purity; and Fractions 8 through 10 were combined to give 157 g ofproduct with 99.5% purity. Yield was 47%.

Formulation Example 1 Formulation of PPC in GBL

This set of procedures is generally applicable in exchanging the polymersolvent from acetone to any higher boiling solvent that is miscible withpoly(propylene carbonate). Commercial poly(propylene carbonate) (PPC,M_(w)=40 k based on gel permeation chromatography measurements) wasobtained in the form of a polymer solution in acetone.Gamma-butyrolactone (GBL) (451 g) is added to the commercialpoly(propylene carbonate) with M_(w)=40 k in acetone (500 g, 36 wt %). Afirst fraction of solvent (221 g) was removed under vacuum (25 mmHg) at54° C. by rotary evaporation. A second fraction of solvent (281 g) wasremoved under vacuum (29 mmHg) at 75° C. by rotary evaporation. Theacetone content of the remaining polymer solution was found to be belowreportable limit (0.05 wt %) by gas chromatography. (If the acetonecontent is above reportable limit, the solvent addition and evaporationcycle will be repeated until the acetone content in polymer solution isbelow reportable limit.) The final polymer solution was filtered througha 1 μm capsule into a particle-free container in a cleanroomenvironment. The container is capped and sealed with stretch tape forstorage. The resin content was determined by removing all the solventfrom a measured initial weight of a polymer solution sample using aFisher Isotemp vacuum oven at 105° C. for 5 hours. The final solidpolymer weight was compared to the initial solution weight to determinethe resin content, which was found to be 57 wt %. The viscosity wasdetermined with a Brookfield viscometer (Model DV I Prime) and found tobe 20,000 cPs.

Formulation Example 2 PPC with a TABG in GBL

In general, formulations of lower viscosity than the solvent exchangedsample as described in Formulation Example 1 are prepared by dilutingthe viscous polymer sample with the carrier solvent typically insertedwith an additive. As an example, thermally activated base generatorPT-393 (0.28 g) in GBL (total solution weight 12.0 g) is added to asample solution (19 g, 49 wt %) prepared following Example 1 to give aformulation of 30 wt % with 3 parts per hundred resin (pphr) of thethermally activated base generator. The formulation is roller mixed for12 h and filtered through a 0.2 μm capsule into a particle-freecontainer in a cleanroom environment. The container is capped and sealedwith stretch tape.

Formulation Example 2a PPC with a TABG and Formic Acid in GBL

Formulations with formic acid (FA) were prepared in an analogous mannerto that of Formulation Example 2 but with the addition of formic acid.As an example, neat FA (0.96 g) was added to the polymer solution fromFormulation Example 2. The solution was roller mixed for 12 h andfiltered through a 0.2 μm capsule into a particle-free container in acleanroom environment to give a formulation of 29 wt % resin contentwith 3 pphr PT-393 and 3 wt % FA.

Formulation Examples 3-31 Thermogravimetric Analyses of Formulated PPC

The preparation procedures for the formulations in these examples areanalogous to that of Formulation Example 2. For all the examples in thisseries, the data collected is summarized in Tables 3 and 3a, below.

For each formulation the carrier solvent is GBL and either Novomerpolypropylene carbonate have a molecular weight of either 40,000 (40 k)or 160,000 (160 k) was used. In addition, the specific TABG employed foreach formulation and its loading in parts per hundred of the polymer(pphr) are provided.

Once the formulation was completed, it was spin-coated onto a four-inchsilicon wafer at 1000 rpm. The coated wafer was then soft-baked for 5minutes at 120° C. to give an approximately 5 μm thick film. Portions ofthe resultant uniform wafer film is lifted off the wafer, weighed intoan aluminum pan (3 mg), and subjected to dynamic thermogravimetricanalysis. The film material is heated at a ramp rate of 10° C./min from25 to 500° C. while the temperature at a certain percent weight loss isrecorded. The 50% weight loss temperature (T_(d50)) is 154° C. Acollection of T_(d50) data is summarized in Table 3. The T_(d50) forunformulated poly(propylene carbonate) is 252° C.

TABLE 3 Summary of T_(d50) Data of Formulated PPC Thermally Load- Exam-Polymer Activated Base ing ple M_(w) Generator (pphr) T_(d50) (° C.) 340k PT-393 5.0 154 4 40k PT-393 3.0 163 5 40k PT-393 2.0 177 6 40kPT-393 1.0 183 7 40k PT-393 1.0** 123 8 40k PT-393 0.5 191 9 40k PT-3930.5** 121 10 40k PT-407M 5.0 179 11 40k PT-407M 3.0 186 12 40k CXC-17615.0 255 13 40k CXC-1761 3.0 254 14 40k Et₄N OAc•4H₂O 1.0 149 15 40k Et₄NOAc•4H₂O 0.75 152 16 40k Et₄N OAc•4H₂O 0.5 152 17 40k Et₄N OAc•4H₂O 0.25146 18 40k — — 252 19 160k  PT-393 3.0 177 20 160k  PT-393 1.7 188 21160k  PT-393 1.0 200 22 160k  PT-393 1.0** 148 23 160k  PT-393 0.5 20724 160k  PT-393 0.5* 163 25 160k  PT-407M 3.0 188 26 160k  CXC-1761 3.0255 27 160k  Et₄N OAc•4H₂O 1.0 162 28 160k  Et₄N OAc•4H₂O 0.75 165 29160k  Et₄N OAc•4H₂O 0.5 175 30 160k  Et₄N OAc•4H₂O 0.25 183 31 160k  — —252 *0.25 phr Et₄N OAc•4H₂O added; **0.5 phr Et₄N OAc•4H₂O added

Examples 18 and 31 were controls in that no TABG was added. As shown,both controls had a T_(d50) of 252° C. Significant lowering of theT_(d50) is seen for all formulation except for those that used CXC-1761.Also the expected higher T_(d50) of each higher M_(w) analog and thelower T_(d50) for the more highly TABG loaded analogs is seen.Unexpected, however, is the dramatic effect of the addition of a smallamount of Et₄N OAc.4H₂O to each of Examples 7, 9, 22 and 24 as comparedto the analogous samples without the tetraethylamine salt.

Since the polymer composition embodiments in accordance with the presentinvention are expected to be sacrificial materials that upon heating toan effective temperature will decompose leaving little or no residue,the following Examples, summarized in Table 4, report the percentdecomposition of the various formulations.

Formulation Examples 31-53 Thermal Decomposition of Formulated PPC

The formulation and wafer film preparation for this series of examplesare similar to those described in Formulation Example 3 except the spinspeed is increased to 3000 rpm for 2 μm thick film. The initial filmthickness is measured by profilometry. The wafer film is subjected tothermal decomposition by heating each sample to in an oven. The letterappearing adjacent the Example Number is indicative of the heating cycleused for that Example. Thus for ‘a’ heat to 230° C. in less than orequal to 2 minutes and then holding the plate at that temperature for anadditional 2 minutes; for ‘b’ heat to 240° C. and hold for 10 min; andfor ‘c’ heat to 200° C. and hold for 10 min. For each Example the waferswere removed from the oven allow to cool to room temperature. Residuethickness of the residue on the wafer was subsequently measured and thepercent material decomposed was calculated using the ratio of theresidue thickness and the initial film thickness of the soft-bakedsample. As it can be seen, all of the Examples demonstrated greater than90% decomposition regardless of the initial film thickness, suggestingthat the decomposition cycles employed were adequate and would requireonly minor experimentation to fine tune.

TABLE 4 Summary of Thermal Decomposition Data with Formulated PPCThermally Initial film Load- % Exam- Polymer Activated Base thicknessing Decom- ple M_(w) Generator (μm) (pphr) posed 32a 40k PT-393 2.8 5.099.6 33a 40k PT-393 2.7 3.0 98.3 34b 40k PT-393 6.9 3.0 >99.8 35b 40kPT-393 6.2 2.0 >99.8 36b 40k PT-393 6.0 1.0 >99.8 37b 40k PT-393 4.21.0** 99.5 38b 40k PT-393 6.8 0.5 99.8 39b 40k PT-393 3.7 0.5** 99.2 40c40k PT-393 6.8 3.0 99.8 41c 40k Et₄N OAc•4H₂O 6.0 0.25 >99.8 42c 40kEt4N OAc•4H2O 5.4 0.5 >99.8 43a 40k — 2.3 — 98.7 44b 160k  PT-393 5.23.0 99.6 45b 160k  PT-393 5.4 2.0 98.9 46b 160k  PT-393 4.6 1.0 99.8 47b160k  PT-393 3.8 1.0** 99.3 48b 160k  PT-393 4.6 0.5 99.5 49b 160k PT-393 4.0 0.5* 99.3 50c 160k  PT-393 5.2 3.0 99.8 51c 160k  Et4NOAc•4H2O 5.9 0.25 >99.8 52c 160k  Et4N OAc•4H2O 5.3 0.5 >99.8 53b 160k — 4.4 — 90.6 *0.25 phr Et₄N OAc•4H₂O added; **0.5 phr Et₄N OAc•4H₂Oadded

Formulation Examples 54-78 Solder Flux Evaluation of PPC Formulations

The formulations in gamma-butyrolactone with a thermally activated basegenerator are prepared following procedures of Formulation Example 2,other than the formulation was dispensed as distinct spots with a27-gauge needle onto a copper substrate (1.7 cm×3.4 cm) with a partlyoxidized surface. A solder ball (Sn(99.3)Cu(0.7); 610 μm in diameter)was carefully transferred to the top of each of the spots on the coppersubstrate and then the entire plate mounted onto a device and heated todetermine the amount of solder reflow exhibited. As the polymercomposition embodiments in accordance with the present invention aredirected to providing fluxing to enable solder interconnection betweenadjacent substrates, determining the amount of solder reflow by themethod described above allows for the different TABG additives and theirloading to be evaluated. For each example, the copper substrate washeated to 230° C. in less than or equal to 2 minutes and then held atthat temperature for an additional 2 minutes before allowing the plateto return to room temperature. It was observed during the transfer ofthe plate carrying the carefully placed solder balls, that each spot ofpolymer composition held the solder ball placed thereon in position,thus demonstrating that such compositions are useful as a tacking agent.The diameter of the solder material was measured after reflow and asobserved the controls, Examples 68 and 78 exhibited essentially nosolder spread. Also, the low TABG loadings of Examples 66 and 69 for theEt₄N OAc.4H₂O TABG as compared to the higher loading for Examples 67 and70 seem to indicate that the Et₄N OAc.4H₂O requires a higherconcentration of TABG to achieve adequate solder spread. It should alsobe observed from Table 5, that both formic acid and Et₄N OAc.4H₂O asadditives to PT-393 have little if any effect on the solder spreadobserved for those samples as compared to analogous samples without suchadditives.

TABLE 5 Summary of Solder Flux Data with PPC Formulations in GBLThermally Load- Solder diameter Exam- Polymer Activated Base ing afterthermal ple M_(w) Generator (pphr) reflow (μm) 54 40k PT-393 0.5 1117 5540k PT-393 0.5** 1086 56 40k PT-393 1.0 1135 57 40k PT-393 1.0** 1098 5840k PT-393 2.0 1129 59 40k PT-393 3.0 1188 60 40k PT-393 5.0 1244 61 40kPT-393 5.0† 1191 62 40k PT-393 5.0‡ 1209 63 40k PT-393 8.0 1209 64 40kPT-407M 3.0 1098 65 40k PT-407M 8.0 1111 66 40k Et₄N OAc•4H₂O 0.5 612 6740k Et₄N OAc•4H₂O 1.3 1086 68 40k — — 591 69 160k  Et₄N OAc•4H₂O 0.5 66270 160k  Et₄N OAc•4H₂O 1.3 1043 71 160k  PT-393 0.5* 1074 72 160k PT-393 1.0** 1117 73 160k  PT-393 3.0 1098 74 160k  PT-407M 5.0 982 75160k  PT-407M 8.0 1117 78 160k  — — 610 †3 wt % formic acid added; ‡5 wt% formic acid added; *0.25 phr Et₄N OAc•4H₂O added; **0.5 phr Et₄NOAc•4H₂O added

Formulation Examples 79-126 Storage Stability of PPC Formulations

The formulations in anisole of both the 40K and 160K Mw PPC Novomerpolymer, with the various TABGs, were prepared in the manner of Example2. As an example, a formulation of M_(w)=40 k poly(propylene carbonate)with PT-393 as the additive at 3 pphr loading in gamma-butyrolactone isprepared and its M_(w)(Before) is determined by GPC. The formulation iskept at 25° C. for two weeks, and the M_(w)(After) is determined. TheM_(w) ratio in Table 6 is determined by M_(w)(After)/M_(w)(Before) to be0.99. A M_(w) ratio within the range of 0.95 to 1.05 is indicative thatthe formulation is stable for the stored period within experimentalerror. As shown, it was found that the stability of the compositions inExamples 95-102 were significantly worse than for the compositions thatincorporated PT-393 as a TABG whether or not such compositions includedformic acid (92 and 93) or the addition of Et₄N OAc.4H₂O (80a, 82a, 113and 116). A list of storage stability data is summarized in Table 6.

TABLE 6 Summary of Storage Stability Data with PPC Formulations in GBLM_(w) Example Polymer Additive Loading Temp Time Ratio 79 40k PT-393 0.525 2 1.03 80 40k PT-393 0.5 25 5 1.01  80a 40k PT-393 0.5** 25 2 1.00 8140k PT-393 1.0 25 2 1.01 82 40k PT-393 1.0 25 5 1.01  82a 40k PT-3931.0** 25 2 1.02 83 40k PT-393 2.0 25 2 0.96 84 40k PT-393 2.0 25 5 0.9985 40k PT-393 3.0 25 2 0.99 86 40k PT-393 3.0 25 4 0.96 87 40k PT-3933.0 25 8 1.01 88 40k PT-393 3.0 25 24 1.04 89 40k PT-393 5.0 25 2 0.9990 40k PT-393 5.0 25 4 0.98 91 40k PT-393 5.0 25 8 0.95 92 40k PT-3935.0 25 24 0.96 93 40k PT-393/FA 5.0/3.0^(†) 25 2 1.01 94 40k PT-393/FA5.0/3.0^(†) 25 8 1.01 95 40k PT-407M 3.0 25 2 0.98 96 40k PT-407M 3.0 255 0.99 98 40k PT-407M 3.0 25 16 0.85 99 40k PT-407M 5.0 25 16 0.75 100 40k Bu₄N OAc 1.5 25 1 0.98 101  40k Bu₄N OAc 1.5 25 2 0.77 102  40k Bu₄NOAc 1.5 25 4 0.55 103  40k Et₄N OAc•4H₂O 0.25 25 2 1.02 104  40k Et₄NOAc•4H₂O 0.25 25 5 1.01 105  40k Et₄N OAc•4H₂O 0.5 25 2 0.97 106  40kEt₄N OAc•4H₂O 0.5 25 5 0.95 107  40k Et₄N OAc•4H₂O 0.75 25 2 0.96 108 40k Et₄N OAc•4H₂O 0.75 25 5 0.74 109  40k Et₄N OAc•4H₂O 1.0 25 2 0.81110  40k Et₄N OAc•4H₂O 1.0 25 5 0.60 111  160k  PT-393 0.5 25 2 1.02112  160k  PT-393 0.5 25 5 1.04 113  160k  PT-393 0.5* 25 2 1.00 114 160k  PT-393 1.0 25 2 0.98 115  160k  PT-393 1.0 25 5 1.01 116  160k PT-393 1.0** 25 2 1.01 117  160k  PT-393 2.0 25 2 1.01 118  160k  PT-3932.0 25 5 1.06 119  160k  PT-393 3.0 25 2 0.99 120  160k  PT-393 3.0 25 51.00 121  160k  Et₄N OAc•4H₂O 0.25 25 2 1.03 122  160k  Et₄N OAc•4H₂O0.25 25 5 1.02 123  160k  Et₄N OAc•4H₂O 0.75 25 2 1.06 124  160k  Et₄NOAc•4H₂O 0.75 25 5 1.05 125  160k  Et₄N OAc•4H₂O 1.0 25 2 1.05 126 160k  Et₄N OAc•4H₂O 1.0 25 5 1.07 ^(†)3 wt % formic acid added; *0.25phr Et₄N OAc•4H₂O added; **0.5 phr Et₄N OAc•4H₂O added

Formulation Examples 127-129 Solder Flux Evaluation ofPolynorbornanediol Carbonate Formulations

Solid cis-exo-2,3-polynorbornane dimethyl carbonate polymer (3.0 g) isdissolved in anisole to give a 10.0 g base polymer solution with 30 wt %resin content. A formulation of the indicated carbonate with theindicated TABG at a 3.0 pphr loading was prepared following proceduresin Formulation Example 2 except that anisole was the solvent employed.As shown, each of Formulation Examples 127-129 demonstrate solderreflow, thus indicating the fluxing effect of the TABG employed. A listof solder flux data is summarized in Table 7.

TABLE 7 Summary of Solder Flux Data with Polynorbornanediol CarbonateFormulations in Anisole Load- Solder diameter Exam- ing after thermalple Polymer Additive (pphr) reflow (μm) 127 cis-exo-2,3- PT-393 3.0 875polynorbornane dimethyl carbonate 128 poly(norbornane PT-393 3.0 1206spirocarbonate) 129 poly(norbornane Bu₄N OAc 1.5 1443 spirocarbonate)

Formulation Examples 130-131 Thermal Decomposition of FormulatedPolynorbornanediol Carbonates

The thermal decomposition of the polycarbonates of Formulation Examples130 and 131 was evaluated. The wafer film preparation and thermaldecomposition measurements for this series of examples was performed aspreviously described for Formulation Examples 31-53 except that a 3.9 μmthick film was generated, and only decomposition cycle ‘a’ was employed.The thermal decomposition data is summarized in Table 8.

TABLE 8 Summary of Thermal Decomposition Data of FormulatedPolynorbornanediol Carbonates Initial film Load- % Exam- thickness ingDecom- ple Polymer Additive (μm) (pphr) posed 130 poly(norbornane PT-3933.9 3.0 99.5 spirocarbonate) 131 poly(norbornane Bu₄N OAc 3.8 1.5 93.4spirocarbonate)

Formulation Examples 132-133 Storage Stability of FormulatedPolynorbornanediol Carbonates

The formulations in anisole with additives are prepared followingprocedures of Formulation Examples 127-129. After preparation, thepolymer M_(w)(Before) was determined by GPC. Each formulation was keptat 65° C. for one week, and the polymer M_(w)(After) was determined. TheM_(w) ratio in Table 9 was determined by M_(w)(After)/M_(w)(Before) tobe 0.95. It is believed that a M_(w) ratio within the range of 0.95 to1.05 is indicative that the formulation is stable for the stored periodwithin experimental error.

TABLE 9 Summary of Storage Stability Data of FormulatedPolynorbornanediol Carbonates Ex- Load- Temper- am- Addi- ing ature TimeM_(w) ple Polymer tive (pphr) (° C.) (week) Ratio 37 poly(norbornanePT-393 3.0 65 1 0.95 spirocarbonate) 38 poly(norbornane Bu₄N 1.5 65 10.95 spirocarbonate) OAc

The data presented in Tables 6-9 includes examples that employed a Bu₄NOAc additive reported in WO2010075232 A1, to LaPointe et al., andentitled “Tunable Polymer Compositions”. This data is provided forcomparative purposes only as it is believed that the Bu₄N cation of suchadditive cannot act in the manner indicated in Scheme 8b.

Comparative Example

A formulation of PPC (M_(w)=160,000) was prepared including a thermalacid generator (TAG), specifically DAN FABA (dimethylaniliniumtetrakis(pentafluorophenyl)borate) at 3.9 pphr loading. As DAN FABA hasa formula weight of 800 (as compared to the formula weight of PT-393 of393) this loading is about 10% higher loading that that of a PPCformulation encompassing a 1.7 pphr loading of PT-393. TGA analysis ofthe TAG containing formulation demonstrated a T_(d50) of 206° C. whileTABG formulation of Formulation Example 20 (shown in Table 3)demonstrated a T_(d50) of 188° C.

Given the lower T_(d50) shown by Formulation Example 20, than for theTAG formulation, it should be clear that TABG's are at least aseffective in reducing the decomposition of a PPC as is a TAG.

By now it should be realized that polymer composition embodiments inaccordance with the present invention have been shown useful for use inthe methods described herein. As presented herein, it is shown that theadditives in such polymer composition embodiments significantly lowerthe decomposition temperature of a polymer composition absent suchadditives, provide fluxing to enhance electrical connectivity through asolder reflow process and exhibit excellent storage properties.

Further it should be realized that both polyalkylene carbonates andpolynorbornanediol carbonates can be employed to form sacrificialpolymer compositions that are effective as both tack and flux agentswhen such compositions encompass an appropriate thermally activated basegenerator (TABG). Still further, it should be realized that theselection of such an appropriate TABG is a function of, among otherthings, it being able to provide a degree of solder spread sufficient toallow for an effective solder connection to be formed between twosubstrates as described above. Additionally, such appropriate TABG mustnot result in polymer degradation, depolymerization or decompositionuntil such is desired. Thus the results shown in Tables 6 and 9 areindicative that some sacrificial polymer compositions can be made thathave remarkable room temperature stability, while Tables 4 and 8demonstrate that such stable polymer compositions are capable of being,essentially, completely depolymerized and or decomposed. Thus, it shouldbe realized that sacrifical polymer composition embodiments thatencompass TABGs, and the sacrificial polymers thereof, have beendisclosed and described herein where such sacrifical polymers andcompositions can be claimed as embodiments in accordance with thepresent invention.

Still further, it should be realized that methods of using suchsacrificial polymer compositions for the forming useful microelectronicor optoelectronic devices or structures thereof that make use of theaforementioned sacrificial polymer composition embodiments of thepresent invention. As previously described, some such device formingembodiments of the present invention encompass providing a first and asecond substrate where each substrate has a surface that encompasses aplurality of first and second metal bumps or contact structures,respectively. It will be understood that each of the first and secondsubstrates can be a microelectronic device such as a semiconductor chipor die so that a chip stack is formed, or that one of such substrates isa semiconductor chip and the other a substrate such as would be employedin forming a “flip-chip” assembly. Such substrates are positioned andheld to one another by the tack properties of such composition, whereeach of the aforementioned plurality of metal bumps, or structures, areappropriately aligned and held in such alignment such that electricalcoupling can be subsequently upon heating the substrates and polymercomposition to an effective temperature, the solder will reflow toprovide the aforementioned electrical coupling, the polymer compositionproviding a fluxing property to enable or enhance such electrical soldercoupling, and where said polymer composition is further depolymerized ordecomposed to leave essentially no residue between said first and secondsubstrates.

The invention claimed is:
 1. A sacrificial polymer compositioncomprising: a polycarbonate selected from polypropylene carbonate or apolynorbornanediol carbonate polymer having a weight average molecularweight of from 2000 to 250,000 Dalton; a thermally activated basegenerator represented by formula IV:

a solvent selected from anisole or gamma butyrolactone; and wherein saidcomposition further comprising from 3 weight percent to 5 weight percentformic acid based on the total weight of the composition.
 2. Thesacrificial polymer composition of claim 1 where the solvent is gammabutyrolactone.
 3. The sacrificial polymer composition of claim 1 wherethe thermally activated base generator loading is from 0.5 parts perhundred polymer to 8 parts per hundred polymer, inclusive.
 4. Thesacrificial polymer composition of claim 1, which further comprises apolycarbonate polymer comprising repeating units derived from one ormore of endo-endo-2,3-norbornanedimethanol,exo-exo-2,3-norbornanedimethanol, endo-exo-2,3-norbornanedimethanol,exo-5-phenyl-exo-exo-2,3-norbornanedimethanol,exo-5-phenyl-endo-endo-2,3-norbornanedimethanol, norbornanespirocarbonate, and phenyl norbornane spirocarbonate.
 5. The sacrificialpolymer composition of claim 2 where the thermally activated basegenerator further comprises Et₄N OAc.4H₂O.
 6. A sacrificial polymercomposition comprising: a polycarbonate selected from polybutylenecarbonate, polycyclohexylene carbonate and a norbornanediol carbonatepolymer derived from a monomer of formula A, B or C:

wherein n is independently 0, 1 or 2, each of R¹, R², R³ and R⁴ isindependently selected from hydrogen or a hydrocarbyl group containingfrom 1 to 25 carbon atoms, each of R⁵ and R⁶ are independently selectedfrom —(CH₂)_(p)—OH, where p is 1, 2 or 3, and each of X and X′ isindependently selected from —CH₂—, —CH₂—CH₂— and —O—, where each X′, ifpresent, oriented the same or opposite the orientation of X; or a blendthereof wherein said polycarbonate having a weight average molecularweight of from 2000 to 250,000 Dalton; a thermally activated basegenerator selected from:

a solvent selected from anisole or gamma butyrolactone; and wherein saidcomposition further comprising from 3 weight percent to 5 weight percentformic acid based on the total weight of the composition.
 7. Thesacrificial polymer composition of claim 6 where the polycarbonate is anorbornanediol carbonate polymer derived from a monomer of Formulae A1,B1 and C1:

wherein: R⁴ is independently selected from an alkyl, cycloalkyl,heteroalkyl, heterocycloalkyl, aryl, heteroaryl or aralkyl group.
 8. Thesacrificial polymer composition of claim 6 where the solvent is gammabutyrolactone.
 9. The sacrificial polymer composition of claim 6 wherethe thermally activated base generator is represented by formula IV:


10. The sacrificial polymer composition of claim 9 where the solvent isgamma butyrolactone.
 11. The sacrificial polymer composition of claim 6where the thermally activated base generator loading is from 0.5 partsper hundred polymer to 8 parts per hundred polymer, inclusive.
 12. Thesacrificial polymer composition of claim 6, where the norbornanediolcarbonate polymer is derived from one or more monomers selected fromendo-endo-2,3-norbornanedimethanol, exo-exo-2,3-norbornanedimethanol,endo-exo-2,3-norbornanedimethanol,exo-5-phenyl-exo-exo-2,3-norbornanedimethanol andexo-5-phenyl-endo-endo-2,3-norbornanedimethanol.
 13. The sacrificialpolymer composition of claim 6 where the thermally activated basegenerator further comprises Et₄N OAc.4H₂O.